The High and Rising Alcohol Content of Wine

Abstract

Initial motivation for the work in this chapter came from an observation that the sugar content of California wine grapes at harvest had increased by more than 9 per cent, from 21.4 degrees Brix in 1980 (average across all wines and all districts) to 23.3 degrees Brix in 2008.1 Sugar essentially converts directly into alcohol, so an 11 per cent increase in the average sugar content of wine grapes implies a corresponding 11 per cent increase in the average alcohol content in wine. Questions arose as to whether the rising sugar content of grapes was indeed reflected in rising alcohol content of wine and whether we could distinguish between causes related to climate change versus other causes related to evolving market preferences, as indicated by expert ratings for wines, and government policies that discourage the production of wine with higher alcohol content.2